收藏｜ Scrapy框架各组件详细设置

scrapy startproject <Project_name>
scrapy genspider <spider_name> <domains>

scrapy genspider –t crawl <spider_name> <domains>

import scrapy
# 有些命令如果有python基础的都明白，我不做过多介绍
import json
# 需要做持久化所以导入item，也可以根据文件夹名慢慢导入
from ..items import DoubanItem

class DoubanSpider(scrapy.Spider):
    name = 'douban'
    allowed_domains = ['douban.com']
    # 对单个爬虫设置请求头
    custom_settings = {  
        'DEFAULT_REQUEST_HEADERS': {
        'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
        'Accept-Language': 'en',
        'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36'
    }}
    
    # 很多时候并不需要重载这个函数，如果需要定制化起始url或者单独设置请求头可以选择重载
    def start_requests(self):
        page = 18
        base_url = 'https://xxxx'
        for i in range(page):
            url = base_url.format(i * 20)
            req = scrapy.Request(url=url, callback=self.parse)
            # 对某个请求添加请求头，后面的请求如果要设置也是类似方法
            # req.headers['User-Agent'] = ''  
            yield req
            
    # 没有特别要解释，就是常规的页面解析抛给...（看数据流就明白了）
    def parse(self, response):
        json_str = response.body.decode('utf-8')
        res_dict = json.loads(json_str)
        for i in res_dict['subjects']:
            url = i['url']
            yield scrapy.Request(url=url, callback=self.parse_detailed_page)
            
    # scrapy的response可以直接用xpath解析，基础东西大家都懂不赘述
    def parse_detailed_page(self, response):
        title = response.xpath('//h1/span[1]/text()').extract_first()
        year = response.xpath('//h1/span[2]/text()').extract()[0]
        image = response.xpath('//img[@rel="v:image"]/@src').extract_first()
        
        item = DoubanItem()
        item['title'] = title
        item['year'] = year
        item['image'] = image
        # 如果要下载图片需要单独设置，ImagePipelines，同样在settings和pipelines都需要相应设置
        item['image_urls'] = [image]   
        yield item

rules = (Rule(LinkExtractor(allow=r'http://digimons.net/digimon/.*/index.html'), callback='parse_item', follow=False),)

import scrapy

class DoubanItem(scrapy.Item):
    title = scrapy.Field()
    year = scrapy.Field()
    image = scrapy.Field()
    # 下载图片的ImagePipelines也需要设置items
    image_urls = scrapy.Field()   
    
    # 持久化存储我选择用mysql，不具体展开
    def get_insert_sql_and_data(self):
    # CREATE TABLE douban(
    # id int not null auto_increment primary key,
    # title text, `year` int, image text)ENGINE=INNODB DEFAULT CHARSET=UTF8mb4;
        insert_sql = 'INSERT INTO douban(title,`year`,image)' \     # 系统关键字需要加``
                     'VALUES(%s,%s,%s)'
        data = (self['title'],self['year'],self['image'])
        return (insert_sql, data)

# 信号，这个名词在scrapy自定义拓展中很重要
from scrapy import signals
# 本地配置的类，代码见后续，可以搭在自己的IP池上，也可以直接挂在收费IP（比如我）
from proxyhelper import Proxyhelper
# 多线程操作同一个对象需要锁，用法就是实例化以后一锁一释放
from twisted.internet.defer import DeferredLock

class DoubanSpiderMiddleware(object): # spider中间件不设置
    pass

class DoubanDownloaderMiddleware(object):
    def __init__(self):
        # 对IP配置的代理和锁都实例化
        self.helper = Proxyhelper()
        self.lock = DeferredLock()

    @classmethod
    def from_crawler(cls, crawler):  # 不修改
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_request(self, request, spider):
        # request的数据流到达下载中间件的时候出发
        self.lock.acquire()
        request.meta['Proxy'] = self.helper.get_proxy()
        self.lock.release()
        return None

    def process_response(self, request, response, spider):
        # 对响应判断，如果不符合就换代理重新请求
        if response.status != 200:   
            self.lock.acquire()
            self.helper.update_proxy(request.meta['Proxy'])
            self.lock.release()
            return request
        return response

    def process_exception(self, request, exception, spider):
        self.lock.acquire()
        self.helper.update_proxy(request.meta['Proxy'])
        self.lock.release()
        return request

    def spider_opened(self, spider):  # 不修改
        spider.logger.info('Spider opened: %s' % spider.name)

import requests

class Proxyhelper(object):
    def __init__(self):
        self.proxy = self._get_proxy_from_xxx()

    def get_proxy(self):
        return self.proxy

    def update_proxy(self, proxy):
        if proxy == self.proxy:
            print('Updating a proxy')
            self.proxy = self._get_proxy_from_xxx()

    def _get_proxy_from_xxx(self):
        url = '' # 此处修改url，最好是一次返回一个ip
        response = requests.get(url)
        return 'http://' + response.text.strip()

# 载入本地的mysql持久化类，按需自己写
from mysqlhelper import Mysqlhelper
# 载入ImagesPipeline便于重载，自定义一些功能
from scrapy.pipelines.images import ImagesPipeline
import hashlib
from scrapy.utils.python import to_bytes
from scrapy.http import Request

class DoubanImagesPipeline(ImagesPipeline):
    def get_media_requests(self, item, info):
        request_lst = []
        for x in item.get(self.images_urls_field, []):
            req = Request(x)
            req.meta['movie_name'] = item['title']  # 获取名字
            request_lst.append(req)
        return request_lst
    # 重载
    def file_path(self, request, response=None, info=None):
        image_guid = hashlib.sha1(to_bytes(request.url)).hexdigest()
        return 'full/%s.jpg' % (request.meta['movie_name']) # 修改图片名

# 无特殊，有些步骤在items已经写完，实现pipelines和items功能上的分离
class DoubanPipeline(object):
    def __init__(self):
        self.mysqlhelper = Mysqlhelper()

    def process_item(self, item, spider):
        if 'get_insert_sql_and_data' in dir(item):
            (insert_sql, data) = item.get_insert_sql_and_data()
            self.mysqlhelper.execute_sql(insert_sql, data)
        return item

# 爬虫名称
BOT_NAME = 'Douban'

SPIDER_MODULES = ['Douban.spiders']
NEWSPIDER_MODULE = 'Douban.spiders'

# 客户端请求头
# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'Douban (+http://www.yourdomain.com)'

# Obey robots.txt rules
# 机器人协定
ROBOTSTXT_OBEY = False

# 并发请求数
# Configure maximum concurrent requests performed by Scrapy (default: 16)
CONCURRENT_REQUESTS = 32


# 下载延迟
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
# 单域名和单IP并发数，会覆盖上面的设定
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
# 对爬虫进行监控
#TELNETCONSOLE_ENABLED = False
# TELNETCONSOLE_ENABLED = True
# TELNETCONSOLE_HOST = '127.0.0.1'
# TELNETCONSOLE_PORT = [6023,]
# 操作命令：cmd -> telent 127.0.0.1 6023-> est<>

# Override the default request headers:
# 默认请求头，项目内所有爬虫有效
# DEFAULT_REQUEST_HEADERS = {
#   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
#   'Accept-Language': 'en',
#   'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36'
# }


# 爬虫中间件
# SPIDER_MIDDLEWARES = {
#    # 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware': None
#    'Douban.middlewares.DoubanSpiderMiddleware': 543,
# }

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
# 下载中间件
DOWNLOADER_MIDDLEWARES = {
   'Douban.middlewares.DoubanDownloaderMiddleware': 560,  
# 更改为560的原因在于不同中间件细分很多亚组间，这些组间的数据大小决定了request和response数据流触碰的顺序，具体见官方文档
}
# 允许url的访问时限
TIMEOUT = 10
# 深度限制
# DEPTH_LIMIT = 1

# 自定义拓展
EXTENSIONS = {
   'Douban.extends.MyExtension': 500,
}


# item-pipelines配置
ITEM_PIPELINES = {
   # 'scrapy.pipelines.images.ImagesPipeline': 1,  # 图片下载器需要注册
   'Douban.pipelines.DoubanImagesPipeline': 300,
}

# 利用算法，自动限速
# Enable and configure the AutoThrottle extension (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# 启用缓存，较少用
# Enable and configure HTTP caching (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

# 图片下载器ImagePipeline的配置，按需开启
IMAGES_STORE = 'download'

from scrapy import signals
from message import Message

class MyExtension(object):
    def __init__(self, value):
        self.value = value

    @classmethod
    def from_crawler(cls, crawler):
        val = crawler.settings.getint('MMMM')
        ext = cls(val)

        crawler.signals.connect(ext.spider_opened, signal=signals.spider_opened)
        crawler.signals.connect(ext.spider_closed, signal=signals.spider_closed)

        return ext

    def spider_opened(self, spider):
        print('spider running')

    def spider_closed(self, spider):
        message = Message('spider运行结束')
        message.push()
        print('spider closed')

from scrapy.cmdline import execute
execute('scrapy crawl douban'.split())